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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,135 records · Page 63
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

SU-E-T-678: Response Calibration Using Electron Depth-Dose Data for MRI-Based 3D Polymer Gel Dosimetry

Purpose: To evaluate a calibration method using the depth-dose data of an electron beam for MRI-based polymer gel dosimetry. Methods: MAGAT was manufactured in-house to fill two 400mL-cylindrical phantoms and nine 22mL-glass vials. Phantom-A was irradiated along the cylinder axis with a 9MeV electron beam of 6 cm x 6 cm field size (FS). Phantom-B was irradiated with a 6MV photon beam of 3 cm x 3 cm FS by a 360-degree arc technique. Eight vials were irradiated in a water-bath to various doses with a 20 cm x 20 cm FS 6MV photon beam. All irradiated phantoms and one un-irradiated vial were scanned with a 3T MRI scanner to obtain the spin-spin relaxation rate (R2) distributions. By comparing the measured R2-to-depth data with the known depth-dose data for Phantom-A, R2-to-dose calibration data were obtained (e-beam method). Another calibration data were obtained from the 9 vials data (9-vial method). We tested two regression equations, i.e., third-order polynomial and tangent functions, and two dose normalization methods, i.e., one-point and two-point methods. Then, these two calibration methods were used to obtain the 3D dose distribution of Phantom-B and evaluated by comparing the measured data with the dose distribution from a treatment planning system. The comparison was made with gamma passing rate (2%/2mm criteria). Results: We did not observe a clear advantage of the e-beam method over the 9-vial method for the 3D dose comparison with the test case. Nevertheless, we found that the e-beam method required a smaller dose scaling for the dose comparison. Furthermore, the tangent function showed better data fitting than the polynomial function with smaller uncertainty of the estimated coefficients. Conclusions: Considering the overall superior performance, we recommend the e-beam method with the tangent function as the regression equation and one-point dose normalization for the MRI-based polymer gel dosimetry.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Dosimetric comparison of stopping power calibration with dual-energy CT and single-energy CT in proton therapy treatment planning

Purpose: The accuracy of proton dose calculation is dependent on the ability to correctly characterize patient tissues with medical imaging. The most common method is to correlate computed tomography (CT) numbers obtained via single-energy CT (SECT) with proton stopping power ratio (SPR). CT numbers, however, cannot discriminate between a change in mass density and change in chemical composition of patient tissues. This limitation can have consequences on SPR calibration accuracy. Dual-energy CT (DECT) is receiving increasing interest as an alternative imaging modality for proton therapy treatment planning due to its ability to discriminate between changes in patient density and chemical composition. In the current work we use a phantom of known composition to demonstrate the dosimetric advantages of proton therapy treatment planning with DECT over SECT. Methods: A phantom of known composition was scanned with a clinical SECT radiotherapy CT-simulator. The phantom was rescanned at a lower X-ray tube potential to generate a complimentary DECT image set. A set of reference materials similar in composition to the phantom was used to perform a stoichiometric calibration of SECT CT number to proton SPRs. The same set of reference materials was used to perform a DECT stoichiometric calibration based on effective atomic number. The known composition of the phantom was used to assess the accuracy of SPR calibration with SECT and DECT. Intensity modulated proton therapy (IMPT) treatment plans were generated with the SECT and DECT image sets to assess the dosimetric effect of the imaging modality. Isodose difference maps and root mean square (RMS) error calculations were used to assess dose calculation accuracy. Results: SPR calculation accuracy was found to be superior, on average, with DECT relative to SECT. Maximum errors of 12.8% and 2.2% were found for SECT and DECT, respectively. Qualitative examination of dose difference maps clearly showed the dosimetric advantages of DECT imaging, compared to SECT imaging for IMPT dose calculation for the case investigated. Quantitatively, the maximum dose calculation error in the SECT plan was 7.8%, compared to a value of 1.4% in the DECT plan. When considering the high dose target region, the root mean square (RMS) error in dose calculation was 2.1% and 0.4% for SECT and DECT, respectively. Conclusions: DECT-based proton treatment planning in a commercial treatment planning system was successfully demonstrated for the first time. DECT is an attractive imaging modality for proton therapy treatment planning owing to its ability to characterize density and chemical composition of patient tissues. SECT and DECT scans of a phantom of known composition have been used to demonstrate the dosimetric advantages obtainable in proton therapy treatment planning with DECT over the current approach based on SECT.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-F-T-220: Validation of Hounsfield Unit-To-Stopping Power Ratio Calibration Used for Dose Calculation in Proton Radiotherapy

Purpose: To validate the stoichiometric calibration of the Hounsfield Unit (HU) to Stopping Power Ratio (SPR) calibration used to commission a commercial treatment planning system (TPS) for proton radiotherapy dose calculation. Methods and Materials: The water equivalent thickness (WET) of several individual pig tissues (lung, fat, muscle, liver, intestine, rib, femur), mixed tissue samples (muscle/rib, ice/femur, rib/air cavity/muscle), and an intact pig head were measured with a multi-layer ionization chamber (MLIC). A CT scan of each sample was obtained and imported into a commercial TPS. The WET calculated by the TPS for each tissue sample was compared to the measured WET value to determine the accuracy of the HU-to-SPR calibration curve used by the TPS to calculate dose. Results: The WET values calculated by the TPS showed good agreement (< 2.0%) with the measured values for bone and all soft tissues except fat (3.1% difference). For the mixed tissue samples and the intact pig head measurements, the difference in the TPS and measured WET values all agreed to within 3.5%. In addition, SPR values were calculated from the measured WET of each tissue, and compared to SPR values of reference tissues from ICRU 46 used to generate the HU-to-SPR calibration for the TPS. Conclusion: For clinical scenarios where the beam passes through multiple tissue types and its path is dominated by soft tissues, we believe using an uncertainty of 3.5% of the planned beam range is acceptable to account for uncertainties in the TPS WET determination.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-F-T-368: Improved HPGe Detector Precise Efficiency Calibration with Monte Carlo Simulations and Radioactive Sources

Purpose: To obtain an improved precise gamma efficiency calibration curve of HPGe (High Purity Germanium) detector with a new comprehensive approach. Methods: Both of radioactive sources and Monte Carlo simulation (CYLTRAN) are used to determine HPGe gamma efficiency for energy range of 0–8 MeV. The HPGe is a GMX coaxial 280 cm{sup 3} N-type 70% gamma detector. Using Momentum Achromat Recoil Spectrometer (MARS) at the K500 superconducting cyclotron of Texas A&M University, the radioactive nucleus {sup 24} Al was produced and separated. This nucleus has positron decays followed by gamma transitions up to 8 MeV from {sup 24} Mg excited states which is used to do HPGe efficiency calibration. Results: With {sup 24} Al gamma energy spectrum up to 8MeV, the efficiency for γ ray 7.07 MeV at 4.9 cm distance away from the radioactive source {sup 24} Al was obtained at a value of 0.194(4)%, by carefully considering various factors such as positron annihilation, peak summing effect, beta detector efficiency and internal conversion effect. The Monte Carlo simulation (CYLTRAN) gave a value of 0.189%, which was in agreement with the experimental measurements. Applying to different energy points, then a precise efficiency calibration curve of HPGe detector up to 7.07 MeV at 4.9 cm distance away from the source {sup 24} Al was obtained. Using the same data analysis procedure, the efficiency for the 7.07 MeV gamma ray at 15.1 cm from the source {sup 24} Al was obtained at a value of 0.0387(6)%. MC simulation got a similar value of 0.0395%. This discrepancy led us to assign an uncertainty of 3% to the efficiency at 15.1 cm up to 7.07 MeV. The MC calculations also reproduced the intensity of observed single-and double-escape peaks, providing that the effects of positron annihilation-in-flight were incorporated. Conclusion: The precision improved gamma efficiency calibration curve provides more accurate radiation detection and dose calculation for cancer radiotherapy treatment.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Poster - 53: Improving inter-linac DMLC IMRT dose precision by fine tuning of MLC leaf calibration

Purpose: To develop a method to improve the inter-linac precision of DMLC IMRT dosimetry. Methods: The distance between opposing MLC leaf banks (“gap size”) can be finely tuned on Varian linacs. The dosimetric effect due to small deviations from the nominal gap size (“gap error”) was studied by introducing known errors for several DMLC sliding gap sizes, and for clinical plans based on the TG119 test cases. The plans were delivered on a single Varian linac and the relationship between gap error and the corresponding change in dose was measured. The plans were also delivered on eight Varian 2100 series linacs (at two institutions) in order to quantify the inter-linac variation in dose before and after fine tuning the MLC calibration. Results: The measured dose differences for each field agreed well with the predictions of LoSasso et al. Using the default MLC calibration, the variation in the physical MLC gap size was determined to be less than 0.4 mm between all linacs studied. The dose difference between the linacs with the largest and smallest physical gap was up to 5.4% (spinal cord region of the head and neck TG119 test case). This difference was reduced to 2.5% after fine tuning the MLC gap calibration. Conclusions: The inter-linac dose precision for DMLC IMRT on Varian linacs can be improved using a simple modification of the MLC calibration procedure that involves fine adjustment of the nominal gap size.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Calibration of X-Ray diffractometer by the experimental comparison method

A software for calibrating an X-ray diffractometer with area detector has been developed. It is proposed to search for detector and goniometer calibration models whose parameters are reproduced in a series of measurements on a reference crystal. Reference (standard) crystals are prepared during the investigation; they should provide the agreement of structural models in repeated analyses. The technique developed has been used to calibrate Xcalibur Sapphire and Eos, Gemini Ruby (Agilent) and Apex x8 and Apex Duo (Bruker) diffractometers. The main conclusions are as follows: the calibration maps are stable for several years and can be used to improve structural results, verified CCD detectors exhibit significant inhomogeneity of the efficiency (response) function, and a Bruker goniometer introduces smaller distortions than an Agilent goniometer.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Bayesian Calibration of the Community Land Model using Surrogates

We present results from the Bayesian calibration of hydrological parameters of the Community Land Model (CLM), which is often used in climate simulations and Earth system models. A statistical inverse problem is formulated for three hydrological parameters, conditioned on observations of latent heat surface fluxes over 48 months. Our calibration method uses polynomial and Gaussian process surrogates of the CLM, and solves the parameter estimation problem using a Markov chain Monte Carlo sampler. Posterior probability densities for the parameters are developed for two sites with different soil and vegetation covers. Our method also allows us to examine the structural error in CLM under two error models. We find that accurate surrogate models can be created for CLM in most cases. The posterior distributions lead to better prediction than the default parameter values in CLM. Climatologically averaging the observations does not modify the parameters’ distributions significantly. The structural error model reveals a correlation time-scale which can potentially be used to identify physical processes that could be contributing to it. While the calibrated CLM has a higher predictive skill, the calibration is under-dispersive.

Bayesian calibration↗
DOE OSTI2020

Dealing with Measurement Uncertainties as Nuisance Parameters in Bayesian Model Calibration

In the presence of model discrepancy, the calibration of physics-based models for physical parameter inference is a challenging problem. Lack of identifiability between calibration parameters and model discrepancy requires additional identifiability constraints to be placed on the model discrepancy to obtain unique physical parameter estimates. If these assumptions are violated, the inference for the calibration parameters can be systematically biased. In many applications, such as in dynamic material property experiments, many of the calibration inputs refer to measurement uncertainties. Here, we develop a metric for identifying overfitting of these measurement uncertainties, propose a prior capable of reducing this overfitting, and show how this leads to a diagnostic tool for validation of physical parameter inference. The approach is demonstrated for a benchmark example and applied for a material property application to perform inference on the equation of state parameters of tantalum.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2022

Computer Model Calibration with Time Series Data Using Deep Learning and Quantile Regression

Computer models play a key role in many scientific and engineering problems. One major source of uncertainty in computer model experiments is input parameter uncertainty. Computer model calibration is a formal statistical procedure to infer input parameters by combining information from model runs and observational data. The existing standard calibration framework suffers from inferential issues when the model output and observational data are high-dimensional dependent data, such as large time series, due to the difficulty in building an emulator and the nonidentifiability between effects from input parameters and data-model discrepancy. To overcome these challenges, we, in this work, propose a new calibration framework based on a deep neural network (DNN) with long short-term memory layers that directly emulates the inverse relationship between the model output and input parameters. Adopting the “learning with noise” idea, we train our DNN model to filter out the effects from data-model discrepancy on input parameter inference. We also formulate a new way to construct interval predictions for DNN using quantile regression to quantify the uncertainty in input parameter estimates. Through a simulation study and real data application with the Weather Research and Forecasting Model Hydrological modeling system (WRF-Hydro), we show our approach can yield accurate point estimates and well-calibrated interval estimates for input parameters.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

FAST Model Calibration and Validation of the OC5-DeepCwind Floating Offshore Wind System Against Wave Tank Test Data

During the Offshore Code Comparison Collaboration, Continued, with Correlation (OC5) project, which focused on the validation of numerical methods through comparison against tank test data, the authors created a numerical FAST model of the 1:50-scale DeepCwind semisubmersible system that was tested at the Maritime Research Institute Netherlands ocean basin in 2013. The OC5 project revealed a general underprediction of loads and motions by the participating numerical models. This paper discusses several model calibration studies that were conducted to identify potential model parameter adjustments that help to improve the agreement between the numerical simulations and the experimental test data. These calibration studies cover wind-field-specific parameters (coherence, turbulence), and hydrodynamic and aerodynamic modeling approaches, as well as rotor model (blade-pitch and blade-mass imbalances) and tower model (structural tower damping coefficient) adjustments. These calibration studies were conducted based on relatively simple calibration load cases (wave only/wind only). The agreement between the final FAST model and experimental measurements is then assessed based on more complex combined wind and wave validation cases. The analysis presented in this paper does not claim to be an exhaustive parameter identification study but is aimed at describing the qualitative impact of different model parameters on the system response. This work should help to provide guidance for future systematic parameter identification and uncertainty quantification efforts.

17 WIND ENERGY↗
DOE OSTI2019

Broadband Outdoor Radiometer Calibration (BORCAL) Process for the Atmospheric Radiation Measurement (ARM) Program: Second Edition

The Atmospheric Radiation Measurement program (ARM) maintains a fleet of monitoring stations to aid in the improved scientific understanding of the basic physics related to radiative feedback processes in the atmosphere, particularly the interactions among clouds and aerosols. ARM obtains continuous measurements and conducts field campaigns to provide data products that aid in the improvement and further development of climate models. All of the measurement campaigns include a suite of solar measurements. The Solar Radiation Research Laboratory at the National Renewable Energy Laboratory supports ARM's full suite of stations in a number of ways, including troubleshooting issues that arise as part of the data-quality reviews; managing engineering changes to the standard setup; and providing calibration services and assistance to the full fleet of solar-related instruments, including pyranometers, pyrgeometers, pyrheliometers, as well as the temperature/relative humidity probes, multimeters, and data acquisition systems that are used in the calibrations performed at the Southern Great Plains Radiometer Calibration Facility. This paper discusses all aspects related to the support provided to the calibration of the instruments in the solar monitoring fleet.

14 SOLAR ENERGY↗
DOE OSTI2026

INL CRMO XRF Special Report No. 3: INL CRMO XRF Calibration Methods for the Analysis of Ceramics and Brick

This report details the analytical methods used by the Idaho National Laboratory Cultural Resource Management Office to characterize ceramic and brick artifacts using X-ray fluorescence spectrometry. More specifically, this report provides details on instrumentation, analysis times, and matrix-specific calibration protocols for ceramic materials. Calibration curves were developed to adjust raw instrumental output for 13 elements using a suite of reference standards made from historic brick borrowed from the Yale Peabody Museum. Calibration curves were validated by plotting predicted values against published reference values for the calibration set as well as a certified soil reference standard (SRM 2711a).

36 MATERIALS SCIENCE↗
DOE OSTI2019

New Strategies for Time Delay Estimation during System Calibration for UAV-Based GNSS/INS-Assisted Imaging Systems

The need for accurate 3D spatial information is growing rapidly in many of today’s key industries, such as precision agriculture, emergency management, infrastructure monitoring, and defense. Unmanned aerial vehicles (UAVs) equipped with global navigation satellite systems/inertial navigation systems (GNSS/INS) and consumer-grade digital imaging sensors are capable of providing accurate 3D spatial information at a relatively low cost. However, with the use of consumer-grade sensors, system calibration is critical for accurate 3D reconstruction. In this study, ‘consumer-grade’ refers to cameras that require system calibration by the user instead of by the manufacturer or other high-end laboratory settings, as well as relatively low-cost GNSS/INS units. In addition to classical spatial system calibration, many consumer-grade sensors also need temporal calibration for accurate 3D reconstruction. This study examines the accuracy impact of time delay in the synchronization between the GNSS/INS unit and cameras on-board UAV-based mapping systems. After reviewing existing strategies, this study presents two approaches (direct and indirect) to correct for time delay between GNSS/INS recorded event markers and actual time of image exposure. Our results show that both approaches are capable of handling and correcting this time delay, with the direct approach being more rigorous. When a time delay exists and the direct or indirect approach is applied, horizontal accuracy of 1–3 times the ground sampling distance (GSD) can be achieved without either the use of any ground control points (GCPs) or adjusting the original GNSS/INS trajectory information.

47 OTHER INSTRUMENTATION↗
DOE OSTI2016

THE CARMA PAIRED ANTENNA CALIBRATION SYSTEM: ATMOSPHERIC PHASE CORRECTION FOR MILLIMETER WAVE INTERFEROMETRY AND ITS APPLICATION TO MAPPING THE ULTRALUMINOUS GALAXY ARP 193

Phase fluctuations introduced by the atmosphere are the main limiting factor in attaining diffraction limited performance in extended interferometric arrays at millimeter and submillimeter wavelengths. We report the results of C-PACS, the Combined Array for Research in Millimeter-Wave Astronomy Paired Antenna Calibration System. We present a systematic study of several hundred test observations taken during the 2009–2010 winter observing season where we utilize CARMA's eight 3.5 m antennas to monitor an atmospheric calibrator while simultaneously acquiring science observations with 6.1 and 10.4 m antennas on baselines ranging from a few hundred meters to ∼2 km. We find that C-PACS is systematically successful at improving coherence on long baselines under a variety of atmospheric conditions. We find that the angular separation between the atmospheric calibrator and target source is the most important consideration, with consistently successful phase correction at CARMA requiring a suitable calibrator located ≲6° away from the science target. We show that cloud cover does not affect the success of C-PACS. We demonstrate C-PACS in typical use by applying it to the observations of the nearby very luminous infrared galaxy Arp 193 in {sup 12}CO(2-1) at a linear resolution of ≈70 pc (0.″12 × 0.″18), 3 times better than previously published molecular maps of this galaxy. We resolve the molecular disk rotation kinematics and the molecular gas distribution and measure the gas surface densities and masses on 90 pc scales. We find that molecular gas constitutes ∼30% of the dynamical mass in the inner 700 pc of this object with a surface density ∼10{sup 4} M{sub ⊙} pc{sup −2}; we compare these properties to those of the starburst region of NGC 253.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

Calibration of the Voyager ultraviolet spectrometers and the composition of the heliosphere neutrals: reassessment

The data harvest from the Voyagers’ (V 1 and V 2) Ultraviolet Spectrometers (UVS) covers encounters with the outer planets, measurements of the heliosphere sky-background, and stellar spectrophotometry. Because their period of operation overlaps with many ultraviolet missions, the calibration of V1 and V2 UVS with other spectrometers is invaluable. Here we revisit the UVS calibration to assess the intriguing sensitivity enhancements of 243% (V1) and 156% (V2) proposed recently. Using the Lyα airglow from Saturn, observed in situ by both Voyagers, and remotely by International Ultraviolet Explorer (IUE), we match the Voyager values to IUE, taking into account the shape of the Saturn Lyα line observed with the Goddard High Resolution Spectrograph on board the Hubble Space Telescope. For all known ranges of the interplanetary hydrogen density, we show that the V1 and V2 UVS sensitivities cannot be enhanced by the amounts thus far proposed. The same diagnostic holds for distinct channels covering the diffuse He i 58.4 nm emission. Our prescription is to keep the original calibration of the Voyager UVS with a maximum uncertainty of 30%, making both instruments some of the most stable EUV/FUV spectrographs in the history of space exploration. In that frame, we reassess the excess Lyα emission detected by Voyager UVS deep in the heliosphere, to show its consistency with a heliospheric but not galactic origin. Our finding confirms results obtained nearly two decades ago—namely, the UVS discovery of the distortion of the heliosphere and the corresponding obliquity of the local interstellar magnetic field (∼40{sup ∘} from upwind) in the solar system neighborhood—without requiring any revision of the Voyager UVS calibration.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

An Eigenvector-Based Method of Radio Array Calibration and Its Application to the Tianlai Cylinder Pathfinder

We propose an eigenvector-based formalism for the calibration of radio interferometer arrays. In the presence of a strong dominant point source, the complex gains of the array can be obtained by taking the first eigenvector of the visibility matrix. We use the stable principle component analysis method to help separate outliers and noise from the calibrator signal to improve the performance of the method. This method can be applied with poorly known beam model of the antenna, is insensitive to outliers or imperfections in the data, and has low computational complexity. It thus is particularly suitable for the initial calibration of the array, which can serve as the initial point for more accurate calibrations. We demonstrate this method by applying it to the cylinder pathfinder of the Tianlai experiment, which aims to measure the dark energy equation of state using the baryon acoustic oscillation features in the large-scale structure by making intensity mapping observation of the redshifted 21 cm emission of the neutral hydrogen (H i). The complex gain of the array elements and the beam profile in the east–west direction (short axis of the cylinder) are successfully obtained by applying this method to the transit data of bright radio sources.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Spitzer IRAC Photometry of JWST Calibration Stars

We present infrared photometry of all 36 potential JWST calibrators for which there is archival Spitzer IRAC data. This photometry can then be used to inform the stellar models necessary to provide absolute calibration for all JWST instruments. We describe in detail the steps necessary to measure IRAC photometry from archive retrieval to photometric corrections. To validate our photometry, we examine the distribution of uncertainties from all detections in all four IRAC channels as well as compare the photometry and its uncertainties to those from models, ALLWISE, and the literature. Seventy-five percent of our detections have standard deviations per star of all observations within each channel of less than 3%. The median standard deviations are 1.2%, 1.3%, 1.1%, and 1.9% in [3.6]–[8.0], respectively. We find less than 8% standard deviations in differences of our photometry with ALLWISE and excellent agreement with literature values (less than 3% difference), lending credence to our measured fluxes. JWST is poised to do groundbreaking science, and accurate calibration and cross-calibration with other missions will be part of the underpinnings of that science.

47 OTHER INSTRUMENTATION↗
DOE OSTI2017

Insights from Synthetic Star-forming Regions. III. Calibration of Measurement and Techniques of Star Formation Rates

Through an extensive set of realistic synthetic observations (produced in Paper I), we assess in this part of the paper series (Paper III) how the choice of observational techniques affects the measurement of star formation rates (SFRs) in star-forming regions. We test the accuracy of commonly used techniques and construct new methods to extract the SFR, so that these findings can be applied to measure the SFR in real regions throughout the Milky Way. We investigate diffuse infrared SFR tracers such as those using 24 μ m, 70 μ m and total infrared emission, which have been previously calibrated for global galaxy scales. We set up a toy model of a galaxy and show that the infrared emission is consistent with the intrinsic SFR using extra-galactic calibrated laws (although the consistency does not prove their reliability). For local scales, we show that these techniques produce completely unreliable results for single star-forming regions, which are governed by different characteristic timescales. We show how calibration of these techniques can be improved for single star-forming regions by adjusting the characteristic timescale and the scaling factor and give suggestions of new calibrations of the diffuse star formation tracers. We show that star-forming regions that are dominated by high-mass stellar feedback experience a rapid drop in infrared emission once high-mass stellar feedback is turned on, which implies different characteristic timescales. Moreover, we explore the measured SFRs calculated directly from the observed young stellar population. We find that the measured point sources follow the evolutionary pace of star formation more directly than diffuse star formation tracers.

79 ASTRONOMY AND ASTROPHYSICS↗